The present invention relates to a camera, and more particularly, to a camera including spotwise photometric means which facilitates taking a picture through a spotwise photometry.
As is well recognized, a photometry used in the prior art practice of cameras may be categorized into an average photometry and a spotwise photometry. In the average photometry, the brightness level of a relatively broad area of an object being photographed is uniformly determined, and provides a passable result for ordinary objects. Accordingly, almost all conventional cameras having a photometry capability employ this technique. By contrast, the brightness level of a restricted area of an object being photographed is determined in a spotwise manner during the spotwise photometry, and such photometry is effectively utilized when it is desired to control the exposure in accordance with either a bright or dark area of an object being photographed which exhibits a high contrast ratio. However, a disadvantage of the spotwise photometry is that a troublesome operation is required and that there is a likelihood that a picture may be taken with improper exposure. Accordingly, when taking a picture of an ordinary object being photographed, the preference of the average photometry over the spotwise photometry is assumed.
It should be realized however that there are a number of objects being photographed in actuality which exhibit high levels of contrast ratio including an object in the rear light, an object or objects on the stage, an object in a composition formed by viewing the exterior through a window or the like. The chance to take a picture of an object exhibiting a high contrast ratio increases with the improvement in the photographing skill of a user. When an object exhibiting a high contrast ratio is photographed with a camera which employs the average photometry, the exposure is controlled in accordance with an average brightness of the object, and hence it is impossible to reflect the intention of a user in composing the picture if it is desired to control the exposure in accordance with the brightness of either a bright or a dark area of such object.
In the prior art practice, when it is desired to take a picture of such a special object, a so-called spotwise exposure meter having a very limited photometry angle is used to determine the brightness of an object being photographed at a plurality of locations thereon, and exposure factors to be used in taking a picture, such as a diaphragm aperture or an exposure period, are determined on the basis of such brightness information as well as the intended composition describing which part of the object should be taken with a proper exposure and what level should be given to a dark area. Where an object being photographed is accessible as when taking a picture in a studio, the exposure factors are determined as a result of determining the brightness of the object at a plurality of desired locations thereon using an exposure meter of incidence type. It will be appreciated however that the use of an exposure meter which is separate from the camera to perform the spotwise photometry when determining the exposure factors represents both a time and labor consuming procedure and disadvantageously requires complicated calculation.
To accommodate for this, a camera is already available which is provided with spotwise photometric means and which permits the entry of brightness values determined by the spotwise photometric means whenever desired, thus enabling an arithmetic operation to be applied to such values to determine an exposure level. However, conventional cameras of the kind described are constructed so that the entry of brightness values is made by operating an entry member and brightness values entered or a resultant value of arithmetic operation are cancelled by operating a reset member. Hence, if the user forgets to operate the reset member after the completion of a photographing operation with the spotwise photometry, a picture with an improper exposure, which is not intended by the user, may be taken as a result of the previous brightness values being left effective to control the exposure during a succeeding operation. Since a photographing operation with the spotwise photometry represents a rare instance, a camera is also proposed which is arranged to reset the spotwise photometric mode automatically after completing a photographing operation with the spotwise photometry, while simultaneously cancelling brightness values entered. With this camera, an inconvenience is disadvantageously caused in that a select member which enables the spotwise photometric mode must be operated after each completion of a photographing operation if it is desired to take a number of pictures in succession in the spotwise photometric mode.
A camera of the kind described above includes a select member which enables the spotwise photometric mode, and an entry member which is operated to enter spotwise brightness values. The fact that these members are separate results in a troublesome operation and stands in the way to realizing a reduced camera size.
On the other hand, considering a camera of automatic exposure control type, the brightness of an object being photographed, which represents one of the exposure factors, is determined and is used to calculate other exposure factors such as exposure period or diaphragm aperture which are effective to produce a proper exposure for the established brightness of the object. By operating a shutter or a diaphragm in accordance with the exposure factor thus determined, the exposure level is controlled to be constant.
However, in conventional cameras of automatic exposure control type, the photometry and the calculation are repeated for each photographing operation. Consequently, if it is desired to take pictures over a plurality of film frames under the same exposure condition, the exposure factor may vary from operation to operation, resulting in a change in the exposure condition.
To accommodate for this, a camera has been proposed which includes a store member which may be operated to select an exposure level storage mode. When the storage mode is selected, exposure factors are automatically stored for use in a next and a subsequent photographing operation.
However, the camera described immediately above is constructed as a prior cocking type which requires the selection of the exposure level storage mode before initiating a photographing operation, the exposure condition of which should be used as a reference during subsequent photographing operations. Hence, if a user desires, after taking a picture, to take another picture under the same exposure condition as the first one, such cannot be realized.